there is a new opensource (GNU GPL) AMR filter pack available for public use. Iíve upgraded the AMR demux and encoder filter with some better timestamp handling and completed the collection by adding a mux and a decoder filter. So now the package contains a set of Encoder+Decoder and Mux+Demux filters. This makes all kinds of encoding/transcoding into and from AMR format possible.

The filter collection is also available at the public MONOGRAM SVN repository and you can checkout the source code using this command: